#!/bin/bash
STR1="123 is number, ABCis alphabetic & aBC123 is alphanumeric."

echo ${STR1} > test.txt
ls *.{test,txt}

echo "$STR1" | grep -o [[:punct:]] |xargs echo

ls | grep -E "([[:upper:]]){[[::digit]]}?.test?" |tail -n5

exit 0;